Senin, 31 Maret 2014

Designing Your New California Garden: 9. Managing Water – Part 2. Irrigation Systems












Last month (February 2014) we considered several
topics critical to managing your garden water: setting water goals, Water Zone
gardening and capturing/using rainwater. 
If you didn’t catch the February post, we suggest that you read it
before you continue:
http://mother-natures-backyard.blogspot.com/2014/02/designing-your-new-california-garden-9.html.  If you’re new to the ‘Designing Your New
California Garden’ series, you might want to start at the beginning (July, 2013;
http://mother-natures-backyard.blogspot.com/2013/07/designing-your-new-california-garden-1.html
). The monthly posts and exercises introduce you to the ‘New California Garden’
concept and to our example garden at 112 Willow Street.






 






Introduction
and Background



                                                                    






By this point you’ve probably guessed that the
‘irrigation system’ in the New California
Garden
is not likely to be a conventional, one size fits all ‘sprinkler
system’.  Instead it will be tailored to
the Water Zone Plan, site characteristics and the needs of the gardeners
themselves.  Part of the trick to
designing a functional and enjoyable
garden is to look honestly at your own needs and constraints.






Proper watering of native (and other) plants is at
least as important as selecting the right plant for a given water zone.   More native plants die in home gardens due
to improper watering than almost any other cause.  An irrigation system that allows you to water
plants easily and properly is key to a successful garden.  And because your garden will mature – and climate
will change – your irrigation system must also be flexible.  






Your ‘irrigation system’ can be anything from a
simple spigot and hose to a complex automated irrigation system (or some
combination of both).    There’s no one
system that’s right for all gardens.  If
your landscape plan includes more than one Water Zone – or if your site is
anything other than a small flat piece of ground – you may need to use several
types of irrigation methods to water everything properly.   Fortunately, you have several options to
choose from – and plenty of resources to turn to for advice.






 We summarize the benefits, limitations and best
uses for the most common types of irrigation methods used in Southern
California at:
http://www.slideshare.net/cvadheim/irrigation-methods-for-southern-california-gardens   This table reflects our experience with
watering native plants in western Los Angeles County; other experts may present
other points of view.  Realize that the
relative advantages and disadvantages vary with climate, soil and other
factors.  Much of the readily available
information on watering native plants – both on-line and in books - is directed
to gardeners in central & northern California, or in desert areas.  While generally useful, remember that such
information is not specific to our unique climate(s) in western Los Angeles and
Orange Counties.
 






 


Planning
an Irrigation System: Example from 112 Willow St.






It’s easier to plan your own irrigation system once
you’ve seen a worked example.  So let’s
design a new irrigation system for 112 Willow Street.






 


 






The current irrigation system for 112 Willow Street
is shown on the site map (above). The ‘system’ may be similar to your own.  It consists of two separate water lines: one
line that supplies conventional sprinklers (front and back) and a second supplying
4 hose bibs (spigots).   The sprinklers
are controlled by two timers: one for the front yard and one for the back.  The backyard timer has two stations: the
northern part of the backyard (nearest the house; station 1) and the rest
(station 2). 






As discussed before (February, 2014), the front
yard will be left as is for now; the automated sprinkler system will continue
to water this area every 10 days for the near future.  However, in considering the irrigation needs
of the entire yard, we realize that an additional spigot at the east side of
the front yard would greatly facilitate watering the ‘meditation garden’.  We add this to the Irrigation System Map,
even though the installation may take place several years in the future.






  









The backyard sprinkler system won’t need a lot of
modification to make it suitable for irrigating the new lawn (see above).  One sprinkler head is superfluous and another
would be better if moved slightly.  That
and some new, water efficient sprinkler heads with the correct spray radius
(8-10 ft.) and we’re in business.    The sprinkler system will likely provide all
the water needed for the ‘shady seating’ area as well.  If not, we can supplement occasionally with a
hose and sprinkler.  If you need more
information on irrigation systems and their design we highly recommend the
following tutorials:
http://www.irrigationtutorials.com/
.






Planning an irrigation system for the vegetable
garden requires deciding how  the space
will actually be used.  The gardeners
like raised beds, and there’s room for at least two different configurations,
each providing 120-130 square feet of growing space (see below).  The gardeners will consider how to arrange the
raised beds and will design them next month (April 2014).  Whatever the configuration, they’ll want an irrigation
system that’s flexible and as water-wise as possible. 






 









The gardeners decide to use inexpensive ooze-type soaker
hoses, covered with mulch, to water the raised vegetable beds.  This will allow them to water only the planted
areas, leaving the pathways dry.  Installing a hose bib for each bed will give
the most flexibility. The soaker hoses can be attached directly to the hose bib
in each bed. And each bed can be controlled separately, providing the right
amount of water for each crop through the growing season.  






During most of the year, the gardeners will control
the water manually, as needed. This is, in fact, the most water-efficient
method of irrigation.   But what about
during the three week summer vacation when the gardeners are routinely away?






Depending on how we design the irrigation system,
we can have all the beds on a single, multi-station timer or use individual,
battery operated timers for each bed.  In
our experience, many smaller yards, particularly if landscaped with water-wise
plants, don’t require sophisticated (and costly) irrigation systems with
sensors.   Inexpensive hose timers are readily
available, easy to use and work well in many situations.  You can even store them away when they aren’t
needed to extend their life.   For more
advice on timers and sensors see:















The ‘butterfly garden’ area, which is on a 6-9% slope,
has presented an irrigation challenge in the past.   The gardeners plan to install primarily
water-wise plants – and place the most drought-tolerant of these on the drier
top of the slope.  This will go a long
way towards making the area less problematic. 
 But even though the plants will
be Water Zone 2 at maturity, the ‘butterfly garden’ will require summer water during
the establishment phase (likely the first year or two after planting) and
occasionally thereafter. The gardeners will need an irrigation method that is
flexible; and once again, they have several options.






One possibility is to use drip irrigation for the
first few years.  While some native plant
nurseries recommend against drip
irrigation, in fact this method can be useful in some circumstances in our part
of California.   Drip irrigation has come
a long way in the past decade. For a good, thorough tutorial on drip irrigation
see  
http://www.dripirrigation.com/drip_tutorial.php
.  There are many more choices of emitters
including micro-sprinklers and soaker-emitters.  These can be used successfully with California
native plants under certain conditions.  In our experience, drip irrigation is best
used to get plants started or for container plants.   






There are several downsides to drip irrigation.  Drip systems can be costly, particularly if
you pay to have them installed. The emitters can plug – or even pop off –
during irrigation, so gardeners should inspect their emitters regularly for
proper functioning.  Don’t assume your
plants are being watered adequately unless you check your drip system routinely!!
 






As the root systems grow, the emitters need to be
relocated to provide optimal water to the plants. Remember that the root
systems of many native plants expand quickly; failure to move emitters around
growing plants is another common mistake made by home gardeners.






In our experience, simple soaker hoses can also be
used on small garden slopes, provided that drainage is adequate and watering is
done over several days.  The secret is to
water the area, using a slow seep rate, until runoff starts.  After a few times you’ll know just how long
this takes.  Then water again in the next
day or two.  This will provide a good
soaking, and can be repeated every other week, or as needed, during the first
summer.  The advantages of soaker hoses
over drip are several: 1)  lower cost; 2)
lower maintenance requirements;  3) more
even water coverage (good as plant roots grow out); 4) if covered with mulch
they last for years, providing for supplemental water when needed.



 










Because the top of the slope dries out before the
bottom, the gardeners will use several soaker hoses to give them maximal
flexibility.  The soaker hoses will be
installed once the ‘butterfly garden’ is planted to insure good coverage.  After securing the hoses with landscaping
staples (also called ‘landscape fabric pins’ or ‘sod staples’), they will be
covered with mulch.  They will be
connected to the nearby hose bib (spigot) with a hose when in use.   When not in use they will be completely
invisible.






The gardeners could also choose to water the ‘butterfly
garden’ with a sprinkler that attaches to a hose.  There are many options available – including ones
that are quite attractive.  This option
has the advantage of being very flexible; you can just water the dry areas and
not worry about areas that don’t need water. 
 It also provides a good
approximation of rain if you need to water during winter/spring dry spells.






But any type of overhead watering, whether with
conventional sprinklers or those attached to a hose, has several
disadvantages.  First, overhead irrigation
is less water efficient: in dry climates like ours, some water will evaporate
before reaching the ground and more will evaporate from the mulch without
reaching the ground beneath.   The other
disadvantage, particularly for summer watering, is that overhead watering
increases the chance of fungal diseases.  Wet leaves and warm conditions favor the
growth of fungi; and leaf splash can spread fungal spores from one plant to the
next.






As currently envisioned, the ‘meditation area’ will
not need much irrigation once established and the gardeners plan to use stored
rainwater to supply some of the water in the future.   The irrigation system for this area will
depend on the landscape design for this area.  
The back of the neighbor’s garage abuts this area – an ‘ugly view’.   The arrangement of the seating – and choice
of plants – will dictate the irrigation needs for this area.  If the homeowners choose a trellis and vine
to mask the ‘ugly view’ they will need to supply irrigation to the vines.  Native honeysuckle vines would do well and
require only occasional water once established. 
We’ll have to wait to finish the irrigation system for the 'meditation area’.



 










On further review of the ‘near final’ irrigation
plan for 112 Willow, the gardeners decide that having a spigot to water the
meditation garden will be a necessity as soon as that area is installed.  The idea of watering the area from a backyard
spigot doesn’t seem workable.






  






Designing
Your Irrigation Plan









 






We suggest the following steps in designing your irrigation system:






 


  1. Using
    a copy of Site Map 2, map your existing irrigation system









  1. Compare
    your current system with your Water Zone map.









  1. Decide
    what parts of your current irrigation system are compatible with the Water
    Zones in your new garden.   You may be surprised; conventional
    sprinkler systems can sometimes be modified to work.  If parts of the system are no longer
    needed they can be capped off. And new sprinkler heads can decrease water
    loss to evaporation.









  1. Consider
    how you’ll supply water to Water Zones 1 and 2.  Remember that new plants will need to be
    watered for at least one or two summers until they are established – and Zone
    1-2 and 2 plants will need occasional summer water thereafter.    








 






Once you’ve decided on possible irrigation choices we suggest that you
step back and evaluate.  In fact, you may
want to put your plans aside for a day or two. 
Then ask yourself the following questions:






 


·      
Are these choices consistent with the amount of
time/effort you want to spend watering the landscape?






·      
Are they feasible in terms of cost, skills needed
to construct, maintenance requirements?






·      
Look at your Base Map 2; are you sure you haven’t
located irrigation lines where they will interfere with anything critical (like
gas & electric lines).   






·      
Is the ‘system’ flexible (for example, can you
change if the initial method  doesn’t
work well; can you use overlapping systems if you need to water one part of a
Zone a bit more)?






·      
Have you planned enough: spigots?  Sprinkler heads?  controllers?  
Are these in convenient locations? 
 If not, now it the time to do
something about it.






 






Once you’re happy with your plan then construct a final Irrigation Plan
map.   Be sure to note location of
spigots, location of irrigation pipes and sprinkler risers (if any) and the
types of heads, and location of drip irrigation lines and soaker hoses (if any).  






 


Additional Internet Resources





















  









 









 






We
value your comments (below).    You can
also contact us directly at mothernaturesbackyard10@gmail.com .






 






 








 

















 



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